NEWS – An unprecedented triple-dip La-Nina event, extended by climate change, triggered a peculiar trend in the 2022-23 winter season

WHAT HAS BEEN NOTED?

• Study by National Institute of Advanced Studies, Bengaluru
• Air quality improved in north India while peninsular India recorded an increase in pollution levels
• Emphasised that besides local emissions, rapidly changing climate is a significant factor affecting air quality
• Air quality worsened in peninsular Indian cities in the 2022-23 winter season but improved in the northern part of India, contrary to the trends
• Among the north Indian cities, Ghaziabad registered the most significant improvement with a reduction of 33%, followed by Rohtak (30%) and Noida (28%)
• Delhi, being the most critical and landlocked city, showed an improvement of around 10%
• On the other hand, Mumbai recorded the highest deterioration with a 30% increase in PM2.5 levels, followed by other peninsular cities like Coimbatore (28%), Bengaluru (20%), Chennai (12%), etc
• Many North Indian cities almost reached the 5-year target set under the National Clean Air Programme in no time
• The winter of 2022-23 coincided with the last phase of an unusual triple-dip La Niña event, the first in the 21st century. This phenomenon, influenced by climate change, impacted the large-scale wind pattern, playing a decisive role in preventing stagnation conditions in north Indian cities and thus improving air quality
• The dominance of higher northerly winds at the transport level forced an influx, along with relatively slower winds near the surface, trapping pollutants in peninsular India and increasing PM2.5 concentration. Conversely, feeble western disturbances, unique wind patterns, and the absence of rain, clouds, and faster ventilation led to a significant improvement in air quality in the north